Aqueous emulsion copolymers, more especially in water-and oil-dilutable form, for improving the flow properties and pour point depression of crude oils and petroleum fractions and their use

ABSTRACT

The invention relates to aqueous emulsion copolymers of (meth)acrylates of long-chain alcohols in continuous aqueous phase, characterized in that they contain as storable disperse phase copolymers of the following monomer components: 
     at least 50% by weight and preferably at least 60% by weight (meth)acrylates of C 16-30  alcohols 
     0 to 25% by weight and preferably 5 to 10% by weight (meth)acrylates of alcohols containing no more than 8 carbon atoms 
     0.5 to 40% by weight and preferably 1 to 25% by weight olefinically unsaturated mono- and/or dicarboxylic acids or anhydrides containing more than 10 carbon atoms. 
     The invention also relates to the use of these aqueous emulsion copolymers for depressing the pour or flow points of hydrocarbon mixtures, particularly crude oil or petroleum fractions, the described copolymers forming the disperse phase of aqueous emulsion copolymers in a highly concentrated, but readily mobile formulation for incorporation in hydrocarbon mixtures of the described type.

It is known that the flow properties of crude oils and/or petroleumfractions can be improved by the use of limited quantities of syntheticflow aids. It is known that the function of flow aids is to lower theparticular temperature below which solid constituents present in theliquid hydrocarbon mixture, more especially higher paraffins and/orasphaltenes, crystallize out in such quantities that the flowability ofthe hydrocarbon mixtures is permanently impaired. The temperature rangein question is determined by the known methods for determining flowpoint or pour point. Commensurate with its specific composition, eachcrude oil or the petroleum fractions obtained therefrom has its ownparticular flow point which, in the case of the oil pools presentlyregarded as worth developing, is generally below about 20° C. and, forexample, shows values in the range from about 10° to 18° C. Even in thiscase, it can be advisable in practice to use flow aids based on varioussynthetic homopolymers and/or copolymers.

There is extensive prior art on auxiliaries of the type in questionwhich are also known as crystallization inhibitors and which aregenerally obtained by polymerization of olefinically unsaturatedcompounds containing at least partly unbranched saturated hydrocarbonchains with at least 18 carbon atoms, cf. for example DE-AS 22 10 431and DE-OSS 26 12 757, 22 64 328, 20 62 023, 23 30 232, 19 42 504 and 2047 448.

Particular difficulties arise in practice when the flow point of theparticular crude oil or petroleum fraction to be processed assumesextremely high values which, in particular, may reach at least 25° C. oreven 30° C. and higher. Petroleum materials of this type tend tosolidify rapidly, even at ambient temperature. If, for example, pumpingoperations are interrupted only briefly or if relatively lowtemperatures are encountered during transport, for example throughoffshore pipelines, the hydrocarbon material solidifies rapidly into amass which can no longer be pumped, thereby blocking pipelines, pumpsand the like. The situation is complicated by the fact that, in ordersafely to rule out problems of the type described above, it is oftenstipulated in practice that the flow points of the oils or oil fractionsshould be lowered to values below 15° C. and, more particularly, tovalues below 12° C. or even to values below 10° C. It will readily beappreciated that technological difficulties of a very special naturearise when, for example, the flow point of a particular crude oil has tobe lowered from around 33° C. to values distinctly below 10° C. Anotherdifficulty in this regard is that, in general, it is not possible simplyby increasing the quantity of flow promoter added to obtain acorresponding reduction in flow point. Hitherto unresolved interactionsbetween the flow aid and the solidifying constituents of the crude oilare presumably responsible in the sense of a threshold effect for thedesired objective, the particular constitution of the flow aid beingcrucially important to its effectiveness.

In DE-PS (German Patent) No. 3,031,900, copolymers of n-alkylacrylateswith at least 16 C atoms in the alcohol residue and maleic anhydride,with n-alkylacrylate/maleic anhydride molar ratios of 20:1 to 1:10 aredescribed. Compounds of this type are intended for use ascrystallization inhibitors for paraffin-containing crude oils.Numerically presented examples pertain to the use of correspondingcopolymers in a molar ratio of 1:1 to 8:1. Crude oils with inherent pourpoints below 20C are predominantly used. One table of values deals withIndia crude oil, which is known to be a particularly paraffin-richstarting material (interfering paraffin content 15%), and an inherentpour point of 33C. The optimal efficacy of the copolymers used in thisdocument in terms of pour point lowering on this starting material maybe found at an acrylic acid ester/maleic anhydride ratio of 4:1. Thelowest pour points established here fall in the range of 12C.

The object of each of the earlier applications of the applicant, DE3,807,395 and 3,807,394, is the use of selected copolymers of theacrylic and/or methacrylic acid ester types as flow enhancers inparaffin-rich petroleums and petroleum fractions. In the first-mentionedapplication, the use of copolymers produced from acrylic and/ormethacrylic acid esters of higher alcohols or alcohol cuts with at least16 C atoms in the alcohol residue and no more than 20 wt %, preferablyabout 0.5-15 wt % free acrylic and/or methacrylic acid--wt % based oncopolymer weight--as an additive for crude oil and petroleum fractionscontaining paraffins and or asphaltenes to lower their flow or set pointand improve their flow properties, especially in the temperature rangeshortly above the set point. The flow enhancers are preferably inparaffin-rich oils or oil fractions with inherent pour points above 20°C. and enable these flow points to be reduced to values below 15° C.and, more particularly, to values below 10° C.

The second of the above-mentioned applications describes the use ofcopolymers of acrylates and/or methacrylates of higher alcohols oralcohol cuts containing at least 16 carbon atoms in the alcohol radicaland no more than 5% by weight and preferably from 0.5 to 2.5% by weightmaleic anhydride as flow promoters in paraffin-rich crude oils and/orpetroleum fractions having flow points above 25° C. for reducing theirflow points to values below 15° C. and preferably to values below 10° C.

It is known that the flow promoters from the cited prior art and fromapplicants' earlier applications are used in concentrations in the ppmrange, for example in concentrations of from 20 to 1,000 ppm andpreferably in concentrations of from about 100 to 500 ppm. It is alsoknown that the homogeneous distribution of these extremely lowconcentrations of additives is crucial to the effectiveness of thecopolymers used. In practice, therefore, these flow promoters are usedin solution in suitable organic solvents which provide for immediatemolecular dispersion of the polymer molecules in the hydrocarbonfractions to be treated and for their interaction with the troublesomecomponents thereof, particularly higher paraffins and/or naphthenes.Particulars of suitable solvents can be found in the relevant prior art,for example in DE-PS 30 31 900 cited at the beginning.

The teaching of the invention described in the following is based on aparticular difficulty which acrylate or methacrylatecopolymers--hereinafter referred to as (meth)acrylatecopolymers--present where they are used via oil-soluble solvents whenthe (meth)acrylate component of these copolymers contains at leastconsiderable amounts of, or even predominantly, residues of relativelylong chain alcohols. In the present context, relatively long chainalcohols are understood in particular to be those having a chain lengthin the range from about C₁₆ to C₃₀ and more especially those having achain length of at least C₁₈, particularly when considerable quantities,for example at least about 25% by weight, of alcohols containing atleast 20 carbon atoms are present.

(Meth)acrylate copolymers of this type are particularly effective whenused as flow point promoters or pour point or flow point depressants.Accordingly, it is desirable in principle for the content of(meth)acrylate components containing such long-chain alcohol radicals tobe as high as possible. However, this involves another applicationalproblem: the longer the alcohol radical in the (meth)acrylate componentbecomes, the higher the pour point of the (meth)acrylate copolymer inthe solvent used will become, giving rise to difficulties in thepractical handling and, in particular, in the dosing under in-useconditions of concentrates of the type in question dissolved in organicsolvents. At the present time, experts can only circumvent thesedifficulties by providing and using the flow promoters in comparativelylower concentrations in the solvent and/or by using considerable amountsof comparatively lower alcohols, particularly in the C₁₂₋₁₆ range, inthe production of the (meth)acrylate copolymers. It can be seen thatthere are limitations and disadvantages to both measures.

The solution proposed by the present invention for overcoming theproblem described in the foregoing follows a totally new route from thepractical point of view. The teaching according to the present inventionis based on the surprising observation that the effective use of flowpromoters of the described type does not require preliminary dissolutionof the polymeric (meth)acrylate copolymer compound in an organicsolvent, instead it is possible, particularly under the measuresdescribed in the following in connection with the invention, to use thecopolymers in a totally different formulation. According to theinvention, the polymeric active substances are used in the form ofaqueous emulsion copolymers.

In a first embodiment, therefore, the present invention relates to theuse of pour-point- or flow-point-depressing copolymers of(meth)acrylates of long chain alcohols and ethylenically unsaturatedmono- and/or dicarboxylic acids containing up to 10 carbon atoms oranhydrides thereof and, if desired, limited quantities of(meth)acrylates of short-chain alcohols in the form of the dispersephase of aqueous emulsion copolymers as a highly concentrated, butreadily mobile formulation for incorporation in hydrocarbon mixtures,particularly in crude oil or petroleum fractions.

In another embodiment, the invention relates to water-dilutable andoil-dilutable, mobile aqueous emulsion copolymers of copolymers of(meth)acrylates of higher alcohols containing up to about 30 carbonatoms and ethylenically unsaturated mono- and/or dicarboxylic acids oranhydrides thereof containing up to 10 carbon atoms and, if desired,limited quantities of (meth)acrylates of short-chain alcohols containingas principal components

about 20 to 70% by weight and preferably about 30 to 50% by weightdisperse copolymer phase,

about 0.1 to 7% by weight and preferably about 0.5 to 5% by weightoil-in-water emulsifiers,

up to about 35% by weight water- and oil-soluble solubilizers and/or

up to about 7% by weight water-in-oil emulsifiers and water ascontinuous phase.

Taking into account the hitherto common practice of always addingflow-promoting and pour-point-depressing polymers of the type inquestion here in predissolved form, i.e. predissolved in an organicsolvent, such as toluene, to the crude oils, petroleum fractions orother hydrocarbon mixtures to be treated, the procedure according to theinvention and the comparable or even better results obtained in relationto the prior art are entirely unusual. If it is considered that theadditives are used in ppm concentrations, based on the hydrocarbonmaterial to be treated, and that the effectiveness of these compoundsdepends on an unknown interaction with the troublesome components,particularly the higher paraffins and/or naphthenes, it seems logicaland necessary to introduce the flow-promoting and pour-point-depressingpolymer compounds in activated form into the hydrocarbon material to betreated. This is not the case in the context of the teaching accordingto the invention. In this case, the polymer compounds are present as adisperse, substantially solvent-free, optionally at least partlysolidified organic phase in the homogeneous aqueous phase. When aqueousemulsion polymers of this type are mixed with the hydrocarbon mixture tobe treated, the polymer compound initially has to undergo a phaseinversion. It has to pass from the disperse aqueous phase into thecontinuous organic phase in which it has to dissolve and hence undergothe activation step before finally interacting with the componentsresponsible for the high pour and flow points. The teaching according tothe invention is based on the one hand on the unexpected discovery thatthe desired effect occurs in the hydrocarbon material to be treated evenand precisely when the flow pomoters are used in the described form ofthe emulsion copolymers.

So far as the invention is concerned, however, this affords furtherpractical advantages which make up the other part of the conceptaccording to the invention:

If the copolymeric active substance is provided and used in the form ofan aqueous emulsion copolymer, the flowability of the active substancein practical application will depend upon the particular constitution ofthe copolymer and, to a very large extent, upon its concentration in themixture of aqueous/organic active substances. The viscosity of aqueousemulsion polymers may be controlled in known manner in such a way as toguarantee high flowability at low viscosities and high solidsconcentrations. So far as the (meth)acrylic copolymer is concerned, thismeans above all that it is now safely possible to use (meth) acrylateswith, in particular, long-chain alcohols which give optimal results inregard to pour point and flow point depression without the particularpour points of these auxiliaries in organic solvents having to be takeninto consideration, as was essential in the prior art. At the same time,these copolymers predominantly or even exclusively based on(meth)acrylates with higher alcohols may be used in high concentrationsin practice.

In one preferred embodiment of the invention, the necessary phasereversal during mixing of the aqueous emulsion copolymers with thehydrocarbon mixtures to be treated, particularly crude oil or petroleumfractions, is facilitated and/or accelerated by the co-use of selectedmixture components in the aqueous emulsion copolymers.

A first embodiment in this regard is characterized by the use of aqueousemulsion copolymers of the described type to which additional componentsdistinguished both by solubility in or miscibility with water and bysolubility in or miscibility with oils have been added. Preferredexamples of such components are polyfunctional alcohols and/or ethersdistinguished by their compatibility on the one hand with water and, onthe other hand, with hydrocarbon phases. Typical examples of compoundsof this type are ethylene glycol, its partial ethers with, inparticular, lower monofunctional alcohols and also polyethylene glycolswhich may even be at least partly etherified. Further examples are thepropanediols, although glycerol is particularly preferred. Correspondingpolyfunctional alcohols and/or ethers or partial ethers containing aneven larger number of carbon atoms are also suitable. Other components,for example selected ketones distinguished by miscibility with water andoils, may also be used in addition to or instead of the compoundsmentioned above.

Solubilizers of the type mentioned above are preferably used inquantities of up to about 35% by weight, based on aqueous emulsioncopolymer, more preferably in quantities of at least about 5% by weightand, most preferably, in quantities of at least about 10 to 20% byweight.

In a second embodiment, the phase reversal process in question ispromoted by the addition of water-in-oil emulsifiers to the aqueousemulsion copolymers. This addition is preferably made after thepreparation of the aqueous emulsion copolymers. The w/o-emulsifiers maybe used in addition to or instead of the water- and oil-misciblecompounds of the type mentioned above. The w/o emulsifiers used arenormally added in quantities of up to about 5% by weight, again based onthe aqueous emulsion copolymer. Typical examples of such w/o emulsifiersare the representatives of this known class of compounds which aredescribed in HOUBEN-WEYL, Methoden der organischen Chemie, 4th Edition1959, Vol. I, Part 2, 109/110 and also 113 et seq., cf. in particularthe Table on pages 129 to 136.

The aqueous emulsion copolymers used in accordance with the inventionmay basically have viscosities in a wide range. Since the viscosity ofthese copolymers may be determined inter alia by the solidsconcentration, another possibility of variation is thus available.However, so far as the operation of mixing of the aqueous emulsioncopolymer with reversal of its disperse phase and dissolution in thehydrocarbon mixtures to be treated is concerned, it is of advantage touse materials which are distinguished by comparatively low viscosityvalues. These low viscosity values may exist as such in the aqueousemulsion copolymer, although if desired they may also be established bydilution of relatively high-viscosity aqueous emulsion copolymers withwater and/or an aqueous/organic phase of water and auxiliary solvent,for example of the above-described type of polyfunctional alcoholsand/or ethers thereof. Viscosity values of the aqueous emulsioncopolymers of at most about 10,000 mPa.s are preferred for processing,viscosity values not exceeding about 5,000 mPa.s being particularlypreferred. Materials of which the flowability approaches that of water,i.e. for example materials having viscosity values in the range fromabout 100 to 3,000 mPa.s, are particularly suitable. All the viscosityvalues cited here are Brookfield viscosities (RTV, 20° C., 20 r.p.m.).

(Meth)acrylate copolymers of the described type, in which the alcoholradicals are predominantly or exclusively long-chain alcohol radicalshaving preferred chain lengths of at least C₁₆ and preferably of atleast C₂₀, are particularly suitable for the teaching of the invention.At least 50 mol-% and preferably at least 80 mol-% of radicals of thistype are present in the long-chain alcohol mixtures normally used forthe preparation of this monomer component. Preferably, these alcohols oralcohol radicals are predominantly corresponding compounds containingn-alkyl radicals. The alcohols themselves may be of natural and/orsynthetic origin. Corresponding alcohol fractions of natural origin are,for example, fractions predominantly containing behenyl alcohol.

The co-use of acrylic acid and/or methacrylic acid or the othermonocarboxylic acids having C-chains of the above mentioned lengthand/or the co-use of corresponding dicarboxylic acids or anhydridesthereof leads to particularly effective copolymers when comparativelyhigh contents of alcohol radicals containing at least 22 carbon atomsare present in the (meth)acrylate copolymer. Thus, it can be ofadvantage in accordance with the invention to use alcohol cuts of whichthe C₂₂ alcohol content is at least about 25% by weight, preferably atleast about 35% by weight and, more preferably, at least 45% by weightfor the production of the acrylate components. Particularly good flowpoint promoters are obtained when these long-chain alcohol componentsare present in quantities of more than 50% by weight in the alcohol cutsused for the production of the (meth)acrylate component. The percentagesby weight are based on the content of C₂₂ alcohols and, optionally,higher alcohols in the alcohol mixture which has been used for theproduction of the (meth)acrylate components.

Particularly suitable comonomers for the emulsion copolymerization withthe (meth)acrylates of the described type are mono- and/or dicarboxylicacids or anhydrides thereof containing up to 6 carbon atoms.Particularly preferred examples are acrylic acid, methacrylic acid,crotonic acid, itaconic acid, maleic acid, maleic anhydride and/orfumaric acid.

Particularly suitable (meth)acrylate copolymers contain the mono- and/ordicarboxylic acids or anhydrides thereof used as comonomers inquantities of up to about 50% by weight and, preferably, in quantitiesof up to about 40% by weight. The most advantageous quantities may beco-determined by considerations relating to the stability of the aqueousemulsion copolymers formed, although in this case general knowledge ofemulsion copolymerization also has to be taken into account in thisregard and applied to the process used to prepare the active substancemixtures used in accordance with the invention.

It has been found that the production of low-coagulate, storable,aqueous emulsion copolymers of the type in question here with highcontents of (meth)acrylates of long-chain alcohols is more difficult,the higher on the one hand the content of long-chain alcohol radicalsbound in the copolymer molecule and the longer on the other hand thealcohol radicals in question. Accordingly, stability problems can arisein particular when, for example in the context of the problem to besolved by the invention, long-chain alcohols (C₂₂ and longer) are to beincorporated in high concentrations in the copolymer molecule. Standardo/w emulsifiers may not have a sufficient stabilizing effect toguarantee the stable dispersion state required. However, assistance isavailable in the class of copolymers selected in accordance with theinvention simply in the fact that the described mono- and/ordicarboxylic acids or anhydrides thereof are used as comonomers. The useof precisely this class of comonomers leads to additional stabilizationof the disperse organic phase formed during the emulsioncopolymerization. Depending on the composition of the multicomponentmixture used, however, it may be necessary to use comparatively largerquantities of the carboxylic acid components. This applies in particularwhen monocarboxylic acids are exclusively used as comonomers. If thedispersion stability additionally required is to be established throughtheir co-use, it may be necessary to use comparatively largerquantities, for example 20 to 40% by weight of monocarboxylic acid,based on the total weight of the organic components to be polymerized.Dicarboxylic acids and/or anhydrides thereof as comonomers may be usedin comparatively smaller quantities, for example in quantities of fromabout 5 to 20% by weight, based on the total weight of the organiccomponents to be polymerized, and even in these quantities showconsiderable stabilizing effects, even in cases where large proportionsof particularly long-chain alcohol radicals are used in the copolymermolecule.

The above-described linking of dispersion stability to the co-use of,after all, considerable minimum quantities of mono- and/or dicarboxylicacids or anhydrides thereof can lead to a limitation in the free choiceof the copolymer composition solely from the standpoint of optimaleffectiveness in improving the flow properties or depressing the pourpoint and flow point of the mixtures to be treated.

Another embodiment of the invention provides effective assistance inthis regard. It has been found that the problems of inadequate emulsionor dispersion stability of the organic copolymer phase are substantiallyreduced when, in addition to the comonomer components discussed thusfar, a third class of compounds is used in comparatively smallquantities in the copolymerization. The compounds in question are(meth)acrylates of short-chain alcohols. The alcohol component of thesecomonomers preferably has at most 8 carbon atoms and, in particular, islimited to 4 carbon atoms. Typical examples of compounds of this typeare ethyl and/or butyl (meth)acrylate. These (meth)acrylates ofshort-chain alcohols are used in quantities of at most 25% by weight,preferably in quantities not exceeding 20% by weight and more preferablyin quantities not exceeding 15% by weight, based in each case oncomonomer mixture. Effective stabilizing effects, despite a considerablereduction in the content of mono- and/or dicarboxylic acids oranhydrides thereof in the copolymer molecule, are obtained even when thequantity of these lower (meth)acrylates is in the range from about 5 to10% by weight (based on the weight of the copolymer).

This stabilization of the described copolymers based on (meth)acrylatesof long-chain alcohols with a large number of carbon atoms in thealcohol radical and a high concentration of this component in thecopolymer molecule in aqueous dispersion copolymers represents part ofthe present invention which may even be regarded separately from thespecific application covered by the foregoing description of theinvention.

In another embodiment, therefore, the present invention relates tostabilized aqueous emulsion copolymers of (meth)acrylates of long-chainalcohols in continuous aqueous phase, characterized in that the emulsioncopolymers in question contain copolymers of the following monomercomponents as storable disperse phase:

at least 50% by weight and preferably at least 60% by weight(meth)acrylates of C₁₆₋₃₀ alcohols

up to 25% by weight and preferably from 5 to 10% by weight(meth)acrylates of alcohols containing no more than 8 C atoms and

0.5 to 40% by weight and preferably about 1 to 25% by weightolefinically unsaturated mono- and/or dicarboxylic acids or anhydridesthereof preferably containing no more than 10 C atoms.

Particularly preferred aqueous emulsion copolymers are those whichcontain no more than about 10% by weight (meth)acrylates of short-chainalcohols, 0.1 to 15% by weight and more especially about 1 to 10% byweight of the mono- and/or dicarboxylic acids or anhydrides thereof and,for the rest, the (meth)acrylates of the long-chain alcohols as disperseorganic phase in the aqueous emulsion copolymer. For the rest, thegeneral numerical data provided in the foregoing apply to theparticularly preferred composition of the copolymers or rather theirrespective components.

Through the use of aqueous copolymers in the embodiment just described,it is possible to achieve substantially optimal adaptation of thestructure of the copolymer molecule even to the requirements of optimalpour or flow point depression.

The special composition of the particular copolymer types is determinedin particular by their effectiveness in improving the flow behavior ofthe particular hydrocarbon mixture as represented in particular by crudeoil or a petroleum fraction. However, it is often very difficult to makesafe predictions regarding the optimal quantities of acrylate ester andacidic comonomer to be used in each individual case. The optimal mixingratios should therefore be determined from case to case on the basis ofthe hydrocarbon mixture to be treated. The reason for this would appearto lie in the fact that the particular compositions of the crude oils orpetroleum fractions of different origin differ considerably from oneanother and that the mechanism responsible for pour point depression andhence for the improvement in flow properties has not yet been fullyelucidated. As mentioned at the beginning, it is assumed that thecopolymers added in ppm concentrations become active in the sense of athreshold effect in the treated hydrocarbon material, more especially byinteraction with naphthenes and/or higher troublesome paraffincomponents. The formulation selected in accordance with the inventionfor the aqueous emulsion copolymers now makes it possible for the firsttime to achieve substantially problem-free optimization in the structureof the disperse copolymer phase and adaptation thereof to the particularnatural conditions prevailing.

So far as the preferred quantities of, for example, acrylic acid and/ormethacrylic acid in the copolymer are concerned, a broad range of, forexample, from about 1 to 40% by weight, based on the weight of thecopolymer, is suitable. Taking emulsion stability into account,particular significance may be attributed to quantities in the higherpart of this range, for example quantities of from about 15 to 40% byweight and, in particular, quantities of from 20 to about 35% by weightof the monocarboxylic acid(s). On the other hand, it may be desirablefor optimal effectiveness in pour point depression and flow improvementto incorporate comparatively smaller quantities of the monocarboxylicacids in the copolymer, for example quantities of from about 1 to 25% byweight and, more particularly, quantities of from about 5 to 15% byweight, based in each case on the weight of the copolymer.

Where dicarboxylic acids or dicarboxylic acid anhydrides of the maleicanhydride type are used, it may be appropriate to limit comonomers suchas these to quantities of at most about 20% by weight and preferably toquantities of no more than 10% by weight. Maleic anhydride may beprocessed, for example, in quantities of from about 5 to 10% by weight,based on the weight of the copolymer, to very stable emulsion copolymerswhich, at the same time, have an optimal effect in depressing the flowand pour points.

In one particular embodiment, it may be desirable to take thedisclosures of the above-cited earlier applications P 38 07 395.1 (D8141) and P 38 07 394.3 (D 8142) into consideration with regard to thecomposition of the (meth)acrylate copolymers. For these embodiments,therefore, the following observations apply to the composition of thecopolymers:

Particularly suitable copolymers contain, together with the acrylatesand/or methacrylates of higher alcohols or alcohol cuts, approximately0.5 to 15% by weight of the free monocarboxylic acids mentioned,copolymers of the described type containing approximately 1 to 10% byweight free acid being particularly suitable. The most importantcopolymers of the type used in accordance with the invention containacrylic acid and/or methacrylic acid as comonomers in theabove-described copolymers in quantities of from about 1.5 to 5.0% byweight. All these percentages by weight are based on the weight of thecopolymer.

Another preferred embodiment of the invention is characterized by theuse of copolymers of acrylates and/or methacrylates of higher alcoholsor alcohol cuts containing at least 16 carbon atoms in the alcoholradical and no more than 5% by weight maleic anhydride, based on theweight of the copolymer. Copolymers of the type mentioned, which containabout 0.5 to 2.5% by weight and, more particularly, about 1 to 2% byweight maleic anhydride, are particularly suitable for the purposes ofthe invention. Once again, the percentages by weight are based on theweight of the copolymer.

It is part of the teaching according to the invention to adjust the flowpoints of the crude oils and/or petroleum fractions used with theirstarting flow points above 25° C. and, in particular, above 30° C. tovalues below 15° C. and preferably to values below 10° C. by theaddition of the flow promoters defined in accordance with the invention.According to the invention, it is possible for example to achieve flowpoints in the range from about 0° to 10° C. by addition of conventionalquantities of the flow promoters according to the invention. In thisway, even these crude oils or petroleum fractions may be handled withoutinterruption under normal everyday conditions. More particularly,underwater pipelines, distributors and the like can be operated withoutinterruption.

The in-use concentration of the flow promoters according to theinvention is in the conventional range, for example in the range from 20to 1,000 ppm, concentrations in the range from 100 to 500 ppm beingpreferred.

The emulsion copolymerization is carried out in known manner, cf. forexample Ulmanns Enzyklopadie der technischen Chemie, 4th Edition, Vol.19, 132 to 145.

Limited quantities of oil-in-water emulsifiers are used for thepreparation and stabilization of the disperse polymer phase in thecontinuous aqueous phase. Suitable emulsifiers of this type are, inparticular, anionic or nonionic emulsifiers or mixtures thereof. Thus,it is possible for example to use sulfates or sulfonates of long-chainalcohols or alkylphenols and also alkyl benzenesulfonates orsulfosuccinates. The sulfates of reaction products of ethylene oxide and(fatty) alcohols or alkylphenols are also suitable, the startingmaterials preferably being nonionic emulsifiers. Other nonionicemulsifiers are sorbitan esters of long-chain fatty acids, ethoxylatedsorbitan esters of long-chain fatty acids and/or alkyl glycerides. Theemulsifiers may typically be used in quantities of from about 0.01 to 5%by weight and preferably in quantities of from about 0.1 to 3% byweight, based in either case on the weight of the monomers. Suitablefree radical initiators are the usual peroxide compounds, for exampleinorganic persulfate compounds, such as alkali or ammonium persulfate,hydrogen peroxide, organic hydroperoxides, for example benzoyl peroxide,acetyl peroxide, per acids, such as peracetic acid and perbenzoic acid,or even other materials yielding free radicals, such as2,2'-azo-bis-isobutyronitrile. Other auxiliaries such as buffers,inorganic salts and pH regulators may also be used for the emulsionpolymerization.

The copolymerization is typically carried out at temperatures in therange from about 60° to 90° C., although it may also be carried out athigher or lower temperatures.

EXAMPLES 1. General Manufacturing Procedure for Producing DispersionsBased on Poly(behenacrylate-co-maleic acid) Apparatus

The reaction is performed in a standard laboratory apparatus consistingof a double-walled glass reactor, agitator, reflux cooler, and heateddropping funnel.

    ______________________________________                                        Raw Materials                                                                 ______________________________________                                        C16/18-behenyl acrylate*)                                                                         810 9                                                     Maltic anhydride     90 g                                                     Dehydrophen(R) 100*)                                                                              100 g                                                     (NH4)2S208           1 g                                                      Water, dist.        1000 g                                                    ______________________________________                                         *)See information in Table 1)                                            

PROCEDURE

828 g distilled water, 100 g Dehydrophen 100(R), and 90 g maleicanhydride are placed in a reactor and heated to BS-90C within 60 min.243 g molten behenyI acrylate (50C) are added and emulsified for 15 minat an agitator speed of 140 rpm. At this time, 0.4 g ammoniumperoxodisulfate dissolved in 10 g water are added all at once.

Exactly 15 min after this addition, a. an initiator solution consistingof 0.4 g ammonium peroxydisulfate in 160 g water and b. the monomer meltconsisting of 567 g behenyl acrylate are added at constant rates fromtwo separate metering funnels over a period of 30 minutes at atemperature of 50° C.

30 Minutes after the complete addition of monomer and initiator, 0.2 gammonium peroxodisulfate dissolved in 2 g water is added in one portionas post-initiator.

The after-reaction time is 90 minutes.

After the product has been cooled to 20° C., the dispersion is filteredthrough a filter bag (80 μm) and packed.

The filter sack is washed out and, after drying, the coagulate found isexpressed as %-residue, based on total monomer.

The stirring speed during the reaction is 140 r.p.m.

The properties of the dispersion are shown in Table 1 (Example 1).Examples 2 to 11 were carried out in the same way.

                  TABLE 1                                                         ______________________________________                                        Overview of aqueous dispersions of                                            poly(behenyl acrylate-co-maleic acid)                                         ______________________________________                                        Mixture                                                                       Ex-                                                                           am-  Water    BA.sup.2)                                                                             MAH.sup.3)                                                                           EM.sup.4)                                                                           Initiator.sup.5)                                                                     Glycerol                            ple  g        g       g      g     g      g                                   ______________________________________                                        1    1000     810.0   90.0   100   1.0    --                                  2    600      339.5   10.5   50    0.5    --                                  3    500      427.5   22.5   50    0.5    --                                  4    500      418.5   31.5   50    0.5    --                                  5    400      418.5   31.5   50    0.5    100                                 6    500      405.0   45.0   50    0.5    --                                  7    300      495.0   55.0   50    0.5    100                                 8    500      405.0   45.0   50    0.5    --                                  9    677      286.4   71.6   38    0.5    --                                  10   500      360.0   90.0   50    0.5    --                                  11   600      150.0   200.0  50    0.5    --                                  ______________________________________                                                                     Brookfield                                       Properties     Stability of  viscosity                                        Ex-         coagulate  the dispersion                                                                            at                                         am-  S.sup.1)                                                                             content    after storage                                                                             20°C.                                                                        at                                   ple  %      % by weight                                                                              at room temperature                                                                       mPa·s                                                                      min..sup.-1                          1    50     0.2        >218         64   100                                  2    50     100.0      nil         --    --                                   3    50     34.9       >432        --    --                                   4    50     0.5        >197        100   100                                  5    50     100.0      nil         --    --                                   6    50     0.2        >465         60   100                                  7    50     1.4        >453        520    20                                  8    50     0.9         >32         80   100                                  9    50     100.0      nil         --    --                                   10   50     3.8        >429        --    --                                   11   50     --          481         28   100                                  ______________________________________                                         .sup.1) FK = Solids content of the dispersion                                 .sup.2) BA = Behenyl acrylate: In examples 1-7 and 9-11, behenyl acrylate     A was used, and in example 8, behenyl acrylate B, with the following          Cchain distribution:                                                     

    C--chain distribution of the fatty alcohol/%                                                C16    C18      C20    C22                                      Behenyl acrylate A                                                                          16.3   22.9     10.7   46.9                                     Behenyl acrylate B                                                                           1.5    8.6     15.2   68.8                                      .sup.3) MAM = Maleic anhydride                                                .sup.4) EM = Emulsifier (Dehydrophen(R) 100) nonylphenol with ca. 10 mole     EO from Henkel KGaA Dusseldorf                                                .sup.5) Initiator =  Anmonium peroxodisulfate                            

2. General Manufacturing Procedure for Producing Dispersions Based onPoly(behenyl acrylate-co-acrylic acid) APPARATUS

The reaction is performed in a standard laboratory apparatus consistingof a double-walled glass reactor, agitator, reflux cooler, and heateddropping funnel.

    ______________________________________                                        Raw Materials                                                                 ______________________________________                                        C16/18-behenyl acrylate*)                                                                         280 g                                                     Acrylic acid         70 g                                                     Dehydrophen(R) 100*)                                                                               25 g                                                     (NH4)2S208           0.5 g                                                    Water, dist.        600 g                                                     ______________________________________                                         *)See information in Table 1)                                            

PROCEDURE

514 g distilled Hater, 25 g Dehydrophen(R) 100 and 25 g Texapon(R) N 25are placed in a reactor and heated to 85-90C within 60 min. 280 g moltenbehenyl acrylate (50 C) and 70 g acrylic acid are mixed, and 30 wt % ofthis mixture are emulsified for 15 min at an agitator speed of 140 rpm.At this time, 0.2 g ammonium peroxodisulfate, dissolved in 5 g water,are added all at once.

Exactly 15 min after this addition, a. an initiator solution consistingof 0.2 ammonium peroxodisulfate in 180 g water and b. the remaining 70wt % of the monomer salt comprising behenyl acrylate and acrylic acid at50C are added from two separate dispensing funnels within 30 min at aconstant dispensing rate.

30 min after addition of all the monomer and initiator 0.1 g ammoniumperoxodisulfate in 19 water are added all at once as post-initiator.

The post-reaction time is 90 min. Then they are cooled.

The agitator speed during the reaction is 140 rpm.

The properties of the dispersion are summarized in Table 2 (Example 18).Examples 12 to 21 were produced by analogous procedures.

                                      TABLE 2                                     __________________________________________________________________________    Overview of aqueous dispersions of poly(behenyl acrylate-co-acrylic           acid)                                                                         Mixture                                  Properties                                    Monomers       Emulsifiers         Coagulate                                                                            Stability of the                                                              dispersion                      Water                                                                             BA.sup.1)                                                                        AS.sup.2)                                                                         BuA.sup.3)                                                                        EA.sup.4)                                                                         Dis.sup.5)                                                                        DP.sup.6)                                                                         TP.sup.7)                                                                        Initiator.sup.8)                                                                    S.sup.9)                                                                         content                                                                              after storage at           Example                                                                            g   g  g   g   g   g   g   g  g     %  % by weight                                                                          room temperature           __________________________________________________________________________                                                       days                       2    600 339.5                                                                            10.5                                                                              --  --  --  25  25 0.5   40 100    nil                        3    600 280.0                                                                            10.5                                                                              --  59.5                                                                              --  25  25 0.5   40        >213                       4    677 340.1                                                                            17.9                                                                              --  --  35  --  -- 0.5   30 100    nil                        5    600 332.5                                                                            17.5                                                                              --  --  --  --  50 0.5   40 100    nil                        6    600 280.0                                                                            17.5                                                                              52.5                                                                              --  --  25  25 0.5   40        >217                       7    677 286.4                                                                            71.6                                                                              --  --  35  --  -- 0.5   30 100    nil                        8    600 280.0                                                                            70.0                                                                              --  --  --  25  25 0.5   40        >218                       9    500 360.0                                                                            90.0                                                                              --  --  --  50  -- 0.5   50 100    nil                        10   677 250.6                                                                            107.4                                                                             --  --  35  --  -- 0.5   30        >225                       11   677 214.8                                                                            143.2                                                                             --  --  35  --  -- 0.5   30        >227                       __________________________________________________________________________     .sup.1) BA = Behenyl acrylate; Behenyl acrylate with the Cchain               distribution as in Table 1 was used.                                          .sup.2) AS = Acrylic acid                                                     .sup.3) BuA = Butyl acrylate                                                  .sup.4) EA = Ethyl acrylate                                                   .sup.5) Dis = 1:1 mixture of Disponil(R) SUS 90 (sodium alkyl                 acrylEO-sulfosuccinate) and Disponil(R) FES 92 (sodium alkyl other            sulfate)                                                                      .sup.6) DP = Dehydrophen(R) 100 (nonylphonol with ca. 10 noles EO)            .sup.7) TP = Texapon(R) N 25 (sodium lauryl ether sulfate)                    All emulsifiers are products of Henkel KGaA, Dusseldorf                       .sup.8) Initiator = Ammonium peroxodisulfate                                  .sup.9 FK = Solids content of the dispersion                             

3. Transfer of the Polymers Dispersed in Water into Organic Medium

Into the dispersion in accordance with Example 1, the following alcoholsare stirred at room temperature (magnetic agitator, mixing time 10 min):

1 a -

1 b Glycerin, 5 wt %

1 c Glycerin, 10 wt %

1 d Propanediol-1,2, 10 wt %

In each case homogeneous mixtures result. In each case, 5 g of themixture are mixed with 95 g xylene at room temperature, using a magneticagitator (mixing time 10 min). The mixtures are stored until phaseseparation takes place (1.5-4 hr) and the upper, xylene phase separatedwith a separatory funnel. The xylene phase is concentrated byevaporation and the remaining polymer is dried in vacuo at 10 mbar/100°C.

The results of the tests are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Phase reversal of dispersed poly(behenyl acrylate-co-maleic                   acid) particles from the aqueous dispersion to the organic solution                 Emulsification                                                                             Time        Polymer recovered                                    of the dispersion                                                                          required for                                                                              in the xylene                                  Test  in xylene    separation h                                                                              solution t by-weight                           ______________________________________                                        1 a   poor         1           20                                             1 b   moderate     2           38                                             1 c   good         4           71                                             1 d   good         4           29                                             ______________________________________                                    

DETERMINATION OF THE POOR POINTS

The pour points were determined in accordance with ASTM D 97-66 and DIN51 597.

25.0 Bombay crude were kept for 15 minutes at 50° C. in a closed vesselwith 800 ppm of a 50% by weight dispersion of the flow promoter and wereshaken vigorously 5 times at regular intervals. The crude oil thus dopedwas rapidly transferred to a cylindrical glass vessel with an internaldiameter of 27 mm which was then immediately closed and suspended at asufficient depth in a water bath at +36° C.

After 30 minutes, the vessel was inclined slightly to one side andexamined to see whether the sample was free-flowing. The sample was thencooled in steps of 3° C. and the test repeated after each step. The pourpoint was determined by adding 3° C. to the temperature at which thesample ceased to flow, even when the glass vessel was inclined through90°.

The pour point of the untreated Bombay crude determined by this methodis 30° C.

                  TABLE 4                                                         ______________________________________                                        Pour Points in Bombay crude (°C.)                                      Example*)     Pour point (°C.)                                         ______________________________________                                        1              9                                                              3             12                                                              4             12                                                              5             12                                                              ______________________________________                                    

We claim:
 1. A method of reducing the pour-point and flow-point of hydrocarbon mixtures comprising adding thereto a pour-point and flow-point reducing quantity of a water-dilutable and oil-dilutable aqueous emulsion of a copolymer consisting essentially ofA. from about 20 to about 70% by weight of at least on copolymers as a disperse phase in the emulsion which is a copolymer consisting of a (meth)acrylic acid ester of a higher alcohol containing from 16 to about 30 carbon atoms and at least one ethylenically unsaturated monocarboxylic acid or anhydride thereof, dicarboxylic acid or anhydride thereof, or a mixture of the foregoing, wherein said acid or anhydride contains up to 10 carbon atoms, and optionally a (meth)acrylic acid ester of a short-chain alcohol containing up to 8 carbon atoms; B. from about 0.1 to about 7% by weight of at least one oil-in-water emulsifier; C. from 0 to about 35% by weight of a water soluble and oil soluble solubilizer; D. from 0 to about 7% by weight of a water-in-oil emulsifier; and E. water as a continuous phase in the emulsion;wherein the above percentages by weight are based on the aqueous emulsion.
 2. The method of reducing the pour-point and flow-point of hydrocarbon mixtures according to claim 1 wherein in the aqueous emulsion, component A is a copolymer of at least about 50% by weight of (meth)acrylic acid esters of C₁₆₋₃₀ alcohols, from 0 to about 25% by weight of (meth)acrylic acid esters of alcohols having no more than 8 carbon atoms, and from about 0.5 to about 40% by weight of the ethylenically unsaturated acid component.
 3. The method of claim 1 wherein said pour-point and flow-point reducing quantity is from about 20 to about 1,000 ppm.
 4. The method of claim 2 wherein said pour-point and flow-point reducing quantity is in the range of from about 100 to about 500 ppm.
 5. A mixture of hydrocarbons containing from about 20 to about 1,000 ppm of a water-dilutable and oil-dilutable aqueous emulsion of a copolymer consisting essentially ofA. from about 20 to about 70% by weight of at least one copolymer as a disperse phase in the emulsion which is a copolymer consisting of a (meth)acrylic acid ester of a higher alcohol containing from 16 to about 30 carbon atoms and at least one ethylenically unsaturated monocarboxylic acid or anhydride thereof, dicarboxylic acid or anhydride thereof, or a mixture of the foregoing, wherein said acid or anhydride contains up to 10 carbon atoms, and optionally (meth)acrylic acid ester of a short-chain alcohol containing up to 8 carbon atoms: B. from about 0.1 to about 7% by weight of at least one oil-in-water emulsifier; C. from 0 to about 35% by weight of a water soluble and oil soluble solubilizer; D. from 0 to about 7% by weight of a water-in-oil emulsifier; and E. water as a continuous phase in the emulsion;wherein the above percentages by weight are based on the aqueous emulsion.
 6. The mixture of hydrocarbons of claim 5 wherein in the aqueous emulsion, component A is a copolymer of at least about 50% by weight of (meth)acrylic acid esters of alcohols, from 0 to about 25% by weight of (meth)acrylic acid esters of alcohols having no more than 8 carbon atoms, and from about 0.5 to about 40% by weight of the ethylenically unsaturated acid component. 